Self-locking closure operator



Feb. 29, 1944. a o. MARTINSON SELF-LOCKING CLOSURE OPERATOR Filed July 2, 1942' 2 Sheets-Sheet 1 .lllllll-Iallnallll w fizz e Edwin 0. Marizllzson m,

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Patented Feb. 29, 1944 SELF-LOCKING CLOSURE OPERATOR Edwin 0. -Martinson, Champaign, Ill., assignor to The C. S. Johnson Company, Champaign, 111.,

a corporation of Illinois Application July 2, 1942, Serial No. 449,524

3 Claims. (Cl. 121-40) The present invention relates to a novel form of self-locking closure operator.

One object of the invention is to provide a novel fluid actuated closure operator embodying a plunger which is arranged to serve both as a positive lock for the operator and as a valve for controlling admission of pressure fluid to the operator. By utilizing a single plunger for the dual purpose just noted, complete assurance is aiforded that the steps of, first, unlocking, and, second, admission of pressure fluid to the operator to actuate the latter Will take place in the order named, thus insuring safe and accurate operation as well as minimization of parts for the apparatus. I

Another object is to provide a self-locking closure operator of the characterindicated in the preceding statement of object, and in which the combination locking and valve plunger is itself fluid operated in at least one direction.

Still another object is to provide a self-locking closure operator embodying a piston and cylinder actuator in which a combined locking and control valve mechanism therefor is built into the cylinder structure, whereby to eliminate external piping or similar connections from such valve mechanism to the cylinder. In this way a particularly rugged self-contained structure is afforded which is especially free from liability tov 30 damage either from dust and dirt or mechanical damage to piping connections and the like.

Further objects and advantages of the inven tion will be apparent as the following description proceeds, taken in connection with the accompanying drawings, in which:

Figure 1 is a side elevation, partially in section, of a concrete bucket equipped with a pair of self-locking closure operators, each of which embodies the present invention. I

Figs. 2 and 3 are enlarged longitudinal sectional views of the lower end portion of one of the operators for the bucket of Fig. 1, the looking plunger of the operator being shown, respectively, in its locked and unlocked positions.

Fig. 4 is a detail sectional view taken substantially along the line 4--4 in Fig. 3. I

A pair of closure operators, l embodying the present invention have been shown herein (Fig. 1) as applied to a concrete bucket It simply because such a use of these operators is one in which their rugged and self-contained characteristics are particularly desirable in View of the liability of damage in such an installation, resulting from severe usage, falling rock and gravel, etc. it shw d therefore be cl ar t at I. do mi intend in any way to limit the invention to such use of my novel operators. On the contrary, I intend to cover all uses, as well as all alternative or modified constructions, of the operators themselves, falling within the spirit and scope of the present invention as expressed in the appended claims.

Turning now to the particular illustrative us of my operators shown in Fig. 1, the concrete bucket H itself is of well-known form. It com'- prises a generally hopper shaped body l2 having open upper and lower ends, and surrounded by a casing or shroud I3. Such a bucket may be dimensioned to receive several cubic yards 'of mixed concrete for transporting the same. This concrete is loaded into the bucket through its open top and discharged at a desired point by opening a pair of closures M at the lower end of the bucket. A bail t5 fixed on the top of the bucket enables it to be hooked onto a derrick fortrans fer from place to place. The closures M are shown as a pair of doors pivoted at I6 and adapted to be swung, from their closed position shown, outwardly away from each other to open of prime importance in an operator for the 010- sures.

In the present instance the closures or doors 14 are swung to open position by respective ones of the operators it.

Each of these operators is of a fluid-actuated piston and cylinder type and comprises a cylinder l1. pivoted at [8 on a strut 19 of the buckets exterior framework. Slida'ble Within these cylinders are pistons I9 (Fig. 2)

having piston rods 20 which are pivoted at their 4' lower ends by pins 2! (Fig. 1) to brackets 22 rigid with the respective doors I l. Accordingly, when pressure fluid is admitted to the lower ends of the cylinders II, the pistons I9 are forced upward therein, pulling the doors l4 outward to open position. Upon relieving such pressure, the pistons descend and the doors reclose' by'gravity.

The operators ID are, in the novel form herein shown, self-locking when the pistons thereinare in their lowered positions, whereby the doors I4 are positively retained in closed position even when the bucket is heavily loaded. The mechanism for this purpose is described below.

Pressure fluid, for example compressed air, may be supp ed to ihwtwatvrt w fr m ny suitable source (not shown) through a flexible hose 23 (Fig. 1) under the control of a manually operable two-position, three-way pilot valve 24. When the valve 24 is in one position compressed air is admitted from line 23 into branch lines 25 through which it passes to the operators I; and when the valve 24 is shifted to its alternative position the supply of air from line 23 is cut oif and lines are relieved to atmosphere.

Turning now to the matter of detail construction of the exemplary form of the operators H], the two are identical and accordingly a description of one will suflice for both. In particular, the cylinder comprises a tubular body 26 closed at its opposite ends by heads 21. 21 joined by stay-bolts 28. Integral with the lower head 21 is a tubular extension 29 slidably receiving the piston rod 20, a suitable packing gland 3!] for the latter being provided.

To look the piston rod 2|] when the piston I9 is in its lowered or door-closed position (shown in Fig. .2), a plunger 3| is provided. The nose of this plunger is projectible into a peripheral groove 32 in a collar 33 press fitted on the piston rod, this collar being seated against a shoulder on the rod to restrain the collar from sliding along the rod when the load in the bucket I tends to open thedoors 4. A flat 35 on the underside of the plunger nose is shaped to bear against the complemental side wall of the groove 32.

'The plunger 3| is slidable axially within a bore 36 in a housing 31 integral with the lower cylinder head 21. The outer end of the bore 36 is closed by a pair of complemental end plates 38, notched at 33 (Fig. 4) to slidably receive a flattened portion 3 l of the plunger and thus restrain it against rotation while permitting endwise movement. Cap screws 43 hold in place the end plates 38, as well as a cup shaped sealing cover 4|.

A helical compression spring 42 yieldably urges the plunger 3| into locking position. This spring encircles the plunger and is seated between the housing end plates 38 and a collar 43 integral with the intermediate portion of the plunger. Since the spring 42 urges the plunger into locking position, the device will always fail safe, i. e., if the air pressure in line 25 should fail at any time the device will shift automatically to its safe or locked position.

The housing 3? is ported in such manner that the plunger 3| serves not only as a locking element but also as a fluid-operated three-way main control valve for the cylinder Thus the housing 31 is ported at 44 and on opposite sides of the plunger collar 4-3, as well as at 4B, the latter port being disposed intermediate the first two mentioned ports, and is positioned relative to the collar 43 to be alternatively in communication with respective ones of the ports 44, 45 in the corresponding two positions of the plunger 3|. The pressure fluid supply line 25 is connected to the port 44; the port 45 is a relief port leading directly to atmosphere; and the port 46, formed in the end wall of the cylinder opens directly from the bore 36 into the interior of the cylinder. It will thus be seen that when the plunger 3| is in its locked position (Fig, 2) that the interior of the cylinder ii is relieved to atmosphere through ports 46 and 45. On the other hand, when pressure fluid is supplied through port 44, it reacts on the inner face of the plunger collar 43, forcing the plunger 3| to its unlocked position (Fig. 3). In the latter position of the plunger, the collar 3| cuts off communication .irom port 46 to the relief port 45, while pressure port 44 communicates with cylinder port 45 for supplying pressure fluid to the cylinder and thereby raises the piston l9 in the latter.

Inadvertent sticking of the plunger 3| in its locking position is prevented by a restricted bleed passage 41 leading from a point adjacent the pressure port 44 to the inner nose of the plunger. Thus, when the plunger 3| starts to retract under the infiuen'ce of pressure fluid from port 44, suificient pressure fluid is admitted to the end face of the plunger 3| through passage 41 to prevent such a low pressure area at the nose of the plunger as would otherwise tend to interfere with movement of the plunger.

The cycle of operation of the disclosed apparatus will be generally apparent from the foregoing. By way of summary, let it be first assumed that the bucket doors I4 are closed. In such case the pistons |9 are in the lowered position of Fig. 2 and are positively locked by the plungers 3|. To dump the contents of the bucket, the pilot valve 24 is turned to its pressure delivery position. Thereupon pressure fluid passes through lines .25 and ports 44 to the respective locking plunger bores 33, thereby forcing the plungers 3| into their unlocked positions. Upon reaching such unlocked positions, the plungers 3| open the ports 46 for admission of pressure fluid to the cylinders so that the pistons I9 rise and open the doors l4. To reclose the doors M, the pilot valve 24 is restored to its relief position, thereby cutting off the supply of pressure fluid and relieving the inner portions of the plunger bores 36 to atmosphere through ports 44 and lines 25. The springs 42 are thus permitted to thrust the plungers 3| inward to their locking positions. In the latter position the interiors of the cylinders are relieved to atmosphere through ports 46 and 45 so that the pistons l9 may fully descend and restore the doors I4 to closed position. As the pistons finally move into their lowered positions, the beveled lower ends 33 of the collars 33 ride over the beveled noses of the plungers 3|, thrusting the latter outward momentarily so as to permit the collars 3.3 to move clown into the final position of Fig. 3 and in which position the plungers 3| jump back inward into locking engagement with the grooved collars.

Of special note is the extreme compactness and ruggedness of the disclosed structure. In particular, it is to be observed that there is no pipe or other exposed connection from the plunger housing 31 to the cylinder Instead, communication is had through simply the port 48 in the lower cylinder head. Such close coupling of the cylinder and its main control valve prevents damage which would otherwise result from rupture of the connection between them. It is true that there are exposed supply lines 25, but these lead simply from the pilot valve 23 rather than from the main valves and, as here-- tofore pointed ou the apparatus will fail safe even if the lines 25 should be broken.

I claim as my invention:

1. A self-locking closure operator comprising, in combination, a cylinder having a fluid operable piston slidable therein and having a piston rod projecting from one end of the cylinder, a housing rigid with one end of said cylinder and having a bore therein extending transaxially of the piston, a plunger slidable endwise in said bore into and out of locking engagement with said piston rod, spring means yieldably urging said plunger into locking position, said plunger having a circumferential collar portion rigid with the intermediate portion thereof, said housing having pressure fluid inlet and exhaust ports therein leading into said bore on opposite sides of said collar and with the inlet port on the side of said collar adjacent said piston, whereby pressure fluid admitted through said inlet port acts on said collar to shift the plunger into unlocking position against the bias of said spring means, and said housing having an intermediate port therein leading directly into said cylinder and positioned to lie alternatively on opposite sides of said collar in the respective alternative positions of the plunger to establish communication from the cylinder to said exhaust port when the plunger is in looking position and to said inlet port when the plunger is in unlocking position.

2. A self-locking closure operator comprising, in combination, a cylinder, a piston slidable in the cylinder and having a piston rod projecting from one end of the cylinder for connection with the closure to be operated, a housing rigid with said end of the cylinder and having a bore therein disposed transversely of the axis of the cylinder with the inner end of the bore communicating with the interior of the cylinder, a plunger slidable in said bore and spring-pressed into locking engagement with said piston rod so as to hold the rod against axial movement, and means for causing said plunger to shift from locking to unlocking position upon the admission of pressure fluid to said housing, said housing having three ports therein at spaced points along said bore, the intermediate one of said ports leading directly into the interior of said cylinder and the remaining ones of said ports constituting, respectively, a pressure fluid inlet and outlet, said plunger being adapted to establish communication, in its alternative pistonlocking and unlocking positions, between said intermediate port and said outlet and inlet ports, respectively.

3. A self-locking closure operator comprising, in combination, a cylinder having a head at one end with a recess opening into the cylinder axially thereof, a piston in said cylinder having a rod slidable through said head axially of said recess, a keeper member fixed on said rod and adapted to be positioned within said recess when said piston is positioned adjacent said head, a housing rigid with said head and having a bore extending transversely of said axis with the inner end of the bore communicating with said recess, a plunger slidable within said bore and movable into and out of direct locking engagement with said keeper member, and means for causing said plunger to shift from locking to unlocking position upon the admission of pressure fluid to said housing, said housing having three ports therein at spaced points along said bore, the intermediate one of said ports leading directly into the interior of said cylinder and the remaining ones of said ports constituting, 

